It was sad to be losing a landmark, but there were two other large oaks on West St and a replacement would be planted from Farley's Oak seedlings at Collier Reserve in July, she said.
But the Farley family, descendants of those who bought the section on which the oak was planted, doubt the reports.
"Leave it alone and let it do its own thing," said Jim Farley.
His son Allan Farley said there had been aborists' reports over the years and many of them had been contradictory.
He said the tree may just need more pruning and its soil conditions improved.
"They've had people look at it a number of times, and the most recent said 'it's no good and it's going to croak at any moment'," he said.
Mr Farley said he had had informal discussions with the council and community board about the tree, but the tree belonged to the council and were worried it may fall and kill someone. "It's been here as long as the town, that change is going to leave a big gap in the skyline ... there's nothing to replace it in this area, it's becoming a very barren skyscape."
Together with his brother, Ian, Mr Farley has been growing seedlings from Farley's Oak and has about a dozen that are at least 1m high.
One has already been planted on the Lions' walkway on Udy St, and he would like more planted around Greytown with a plaque commemorating the tree, his family and other settlers of the town.
Legend has it the West St oak was planted by one of Greytown's earliest settlers, Benjamin Stevens, who came out from England with the acorns in his pocket although it could have been Joseph Meads, owner of the neighbouring section.